here is a nested test
\begin{one}%
	[%
		optional argument%
	]
	to be nested to be nested
	to be nested to be nested
	to be nested to be nested
	\begin{two}\[ x^2\]
		nested text nested tex nested tex%
			[%
				not an argument%
			]
		nested text nested tex nested tex
		nested text nested tex nested tex
		nested text nested tex nested tex
	\end{two}
\end{one}
\begin{three}%
	{%
		mandatory argument%
	}
	three text
	three text
	three text
\end{three}
\begin{four}%
	{%
		mandatory argument%
	}%
	{%
		second mandatory%
	}
	four text
	four text
	four text
\end{four}
\begin{five}%
	[%
		optional%
	]%
	{%
		mandatory argument%
	}%
	{%
		second mandatory%
	}%
	\{ something else\}
	five text
	five text
	five text
\end{five}
\begin{six}%
	{%
		mandatory argument%
	}
	[%
		optional%
	]
	{%
		second mandatory%
	}%
	[%
		second optional%
	]%
	\{ something else\}
	six text
	six text
	six text
\end{six}
